Powering Payments Across
the Open Internet
Monetize APIs, run campaigns, accept payments & go keyless - all powered by x402.
No subscriptions, no middlemen. Multi-network support included — users can pay from the chain they already use.
New to this standard? Learn the x402 protocol.
Everything You Need
From simple API monetization to advanced agent payments — all in one platform.
Payments & Monetization
Micropayments
Charge from $0.01 per API call with instant settlement
Instant Settlement
Payments settle in under 2 seconds on Solana blockchain
Flexible Pricing
Per-call, per-token, multiply fields, or client-quoted
Free Tier
Offer free calls before payment — zero backend changes
Multiple Facilitators
PayAI, RelAI, AutoIncentive, 0xGasless, and custom support
x402 Protocol
Industry-standard HTTP 402 with v1/v2 compatibility
Integration & Developer Tools
Multi-Chain
Solana, Base, SKALE, Avalanche, Ethereum, Polygon, and more
OpenAPI Support
Upload spec and auto-generate paywalled endpoints
MCP Integration
Native Model Context Protocol support for AI agents
Payment Links
Share a paywall link — no extra integration needed
Management API
Full REST & MCP interface for programmatic API management
Platform & Customization
Custom Domains
Dedicated custom domain per API with white-label branding
Custom Paywall
Fully customizable x402 paywall with your branding
Built-in Wallets
Custodial Solana & EVM wallets — no browser extension needed
Teams
Invite members and manage APIs with role-based access control
How It Works
Get started in minutes, not months
Upload Your API
Upload your OpenAPI spec or define endpoints manually with custom pricing
Configure & Test
Set pricing models, custom domains, paywall branding, and enable MCP or direct API access
Publish & Earn
Publish to marketplace, enable paywall, and receive instant payments
How a paid request works
[1] POST /api/your-endpoint
→ Client sends a request
x402 intercept
[2] VERIFY payment signature
→ Validate micro-payment (e.g., $0.01)
✓ Confirmed in ~200ms
x402 execute
[3] RETURN { data: ... }
→ Response sent to the client
→ Revenue credited to your wallet
SolanaRegister Your API & Earn Per Request
Turn your API into a revenue stream with x402 micropayments. Set your price per call and get paid instantly for every request.
- Upload OpenAPI spec or define endpoints manually
- Flexible pricing: per-call, per-token, or dynamic
- Proxy mode or integrate x402 directly
- MCP support for AI agents integration
Monetize Any URL with Payment Links
Create shareable payment links that paywall any URL. Perfect for content, downloads, webhooks, or any resource you want to monetize.
- No coding required - just paste your URL and set a price
- Customizable paywall with your branding
- Configurable access duration after payment
- Works with all supported networks and facilitators
SolanaLet Users Try Before They Pay
Add a free trial to any monetised API in seconds. RelAI tracks usage per caller and enforces limits transparently — no changes to your backend.
- Per-user call limit — each caller gets their own counter
- Global cap — limit total free calls across all users
- Reset periods — never, daily, or monthly
- AI agents see free tier info in MCP tool descriptions
Solana
RelAIOrganize Links into Campaigns
Group multiple payment links together with shared settings. Perfect for promotions, product bundles, or time-limited offers.
- One network & facilitator for all links in campaign
- Schedule campaigns with start and end dates
- Aggregated stats and revenue tracking
- Bulk management of multiple payment links
Pay for x402 APIs with a Simple API Key
No wallets, no signing, no crypto in your code. Just an API key and a funded account. RelAI handles all payment signing and settlement automatically.
- Dedicated custodial wallets (Solana + EVM) per API key
- Works with any x402-compliant API — Base, SKALE, Avalanche, Solana
- Usage tracking, spending limits, and full payment history
- One line of code — works with any HTTP client
// Before: wallet setup, signing, gas...
const wallet = new Wallet(key);
const permit = await signPermit(...);
const proof = encodePayment(permit);
// After: one line with Metered API Access
const res = await fetch(
`https://api.relai.fi/metered/x
?url=${targetUrl}`,
{ headers: { "X-API-Key": key } }
);
// ✓ Payment handled automatically
// ✓ Works with any x402 APIExtend Your API with Plugins
Drop-in plugins for the @relai-fi/x402 SDK. Add free tiers, cross-chain payments, endpoint protection, and custom logic — all in one line.
Give buyers free API calls before payment kicks in. Per-user limits, global caps, daily/monthly resets — all managed server-side.
- Per-buyer call limits
- Global cap across all users
- Dashboard management
Accept payments from any chain. Buyers on Solana can pay your SKALE API — the SDK handles bridging automatically. Zero config.
- Solana, SKALE Base, Base
- Auto-discovery, no API key needed
- 1% bridge fee, instant payout
Protect buyers from paying for dead endpoints. Shield runs a health check before requesting payment — if unhealthy, returns 503.
- URL probe or custom function
- Cached results, configurable TTL
- Retry-After header for clients
Probes the actual endpoint before payment. Sends HEAD with X-Preflight header — if the endpoint is down, buyers get 503.
- Per-endpoint probing
- Cached per path
- Zero config beyond baseUrl
Tracks failure history and opens the circuit after repeated errors. Zero-latency — no extra HTTP requests.
- Closed → Open → Half-open states
- Per-path or global scope
- Retry-After headers
Auto-credit buyers when paid requests fail. Credits are applied on the next request — or use a custom callback.
- Credit or log mode
- onRefund callback
- RefundEvent with full context
Build your own plugins with the RelaiPlugin interface. Rate limits, analytics, webhooks — hook into any point.
- beforePaymentCheck hook
- afterSettled hook
- Non-blocking, error-safe
Built with Leading Technologies
Powered by trusted partners in the x402 ecosystem
Supported Networks
Deploy your APIs across multiple blockchain networks
Tokenomics
Deflationary tokenomics with auto buybacks, burns, and real utility
5AgHPy5UojpGq6TdtQCNobCZ2tkYmZz4d5p1cqr6pumpLatest from the blog
Dual-Channel Payments: One SDK, Two Protocols - x402 and MPP Side by Side
The @relai-fi/x402 SDK now supports Dual-Channel payments — x402 and MPP (Machine Payment Protocol) running through the same middleware. One protect() call, two payment rails, and every plugin works identically across both.
ERC-8004 Reputation Plugins: On-Chain Trust for Every x402 API
The @relai-fi/x402 SDK now has four ERC-8004 plugins: score(), feedback(), solanaFeedback(), and submitRelayFeedback(). Build verifiable on-chain reputation for your API in minutes.
Your AI Agent Now Has Its Own Wallet
RelAI now supports Crossmint Server Wallets — persistent, backend-controlled wallets that let AI agents pay for services autonomously, without any user session or private key management.